1. Technical Field
The present invention is related generally to the field of enzymology. More particularly, the present invention is related to a protein C activator enzyme.
2. State of the Art
Protein C is a trace plasma protein which has been found to be quite important in the regulation of the hemostatic process. However, protein C is an inactive zymogen which must be "activated" in order to perform its biological functions. In vivo, activation of protein C is thought to occur on the surface of endothelial cells lining the blood vessels by a 1:1 stoichiometric complex of thrombin with the cell surface protein thrombomodulin. In vitro, protein C can be activated by this complex as well as several other enzymes such as thrombin, the Factor X-activating protein from the venom of Vipera russelli (RVV-X), trypsin and other preparations (Klein et al, Biochem. 25:4175-4179, 1986; Stocker et al, Behring Inst. Mitt. 79:37-47, 1986; Martinoli et al, Thromb. Res. 43:253,264, 1986). However, these activators are either relatively inefficient and required in large amounts or are relatively nonspecific and catalyze other reactions at an appreciable rate. In addition, some of these proteases may even be neutralized by antiprotease inhibitors present in the plasma.